Connecting rod of radial piston motor and method of producing same

ABSTRACT

A connecting rod of a radial piston motor comprising a spherical portion, a rod portion and a pad and a method of producing same, wherein the pad is formed separately from the spherical portion and the rod portion beforehand, and interfitting portions are formed in the rod portion and the pad. The rod portion and the pad are connected to each other through the interfitting portions to form therebetween a joint which is welded, to produce the desired connecting rod of a radial piston motor. The provision of the interfitting portions enables the rod portion and the pad to be positioned with a high degree of precision.

BACKGROUND OF THE INVENTION

This invention relates to a connecting rod of a radial piston motorcomprising a spherical portion, a rod portion and a pad, and to a methodof producing same.

In producing connecting rods of radial piston motors of the prior art,difficulties have been experienced in positively securing the rodportion to the pad in a predetermined position of the connecting rod tobe produced. Also, connecting rods of the prior art have had thedisadvantage that the rod portion and the pad undergo deformation afterthey are joined to each other, so that it has been impossible to obtainconnecting rods of radial piston motors which have dimensionalstability.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a connecting rod of aradial piston motor and a method of producing same, wherein its rodportion and its pad are formed with interfitting portions and the rodportion and the pad are joined together by welding after having beenconnected to each other through the interfitting portions.

Another object of the present invention is to provide a connecting rodof a radial piston motor and a method of producing same, wherein its rodportion and its pad can be positively secured to each other in apredetermined position of the connecting rod with a high degree ofprecision.

Still another object is to provide a connecting rod of a radial pistonmotor and a method of producing same, wherein no deformation ordeterioration occurs following production, so that the connecting rodhas dimensional stability.

Still another object of the present invention is to provide a connectingrod of a radial piston motor and a method of producing same, wherein itspad is provided at its inner sliding surface with a layer of mostsuitable bearing material.

A further object of this invention is to provide a connecting rod for aradial piston motor and a method of producing same, wherein theconnecting rod is very easy to manufacture and quite advantageous bothcommercially and industrially.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross sectional view of the connecting rod of aradial piston motor showing one embodiment of the invention of theconnecting rod before having been assembled;

FIG. 2 is a front view of the connecting rod of the radial piston motorshown in FIG. 1, showing the connecting rod after having been assembled;

FIG. 3 is a perspective view of the connecting rod of the radial pistonmotor shown in FIG. 2, showing the connecting rod after the rod portionis joined to the pad by welding;

FIG. 4 is vertical sectional view of the connecting rod of a radialpiston motor representing another embodiment of the invention, showingthe connecting rod before being assembled;

FIG. 5 is a front view of the connecting rod of the radial piston motorshown in FIG. 4, showing the connecting rod after having been assembled;and

FIG. 6 is a perspective view of the connecting rod of the radial pistonmotor shown in FIG. 2, showing the connecting rod after the rod portionhas been joined to the pad by welding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will now be described byreferring to the accompanying drawings. FIGS. 1-3 showing a firstembodiment, wherein FIG. 1 is a vertical sectional view of theconnecting rod before having been assembled, FIG. 2 is a front view ofthe connecting rod after having been assembled and FIG. 3 is aperspective view of the connecting rod showing the rod portion joined tothe pad by welding.

As shown, the connecting rod comprises a spherical portion 1, a rodportion 2 and a pad 3. The pad 3 includes a metallic backing layer 4having a bearing alloy layer 5 bonded or clad to its inner surface. Thebearing alloy layer 5 may be of any bearing material as desired that canbe applied to the inner sliding surface of the pad 3.

The spherical portion 1 is formed integrally with the rod portion 2which has a recess 6 in a predetermined position on its end opposite tothe spherical portion 1 for positioning the rod portion 2 with respectto the pad 3 which has a projection 7 in a predetermined position on itsouter surface 9 to be coupled with said recess 6 for positioning the pad3 with respect to the rod portion 2. A portion 8 is a flat portion onthe outer surface 9 surrounding the projection 7. When the projection 7is inserted in the recess 6 in interfitting relation, a joint 10(component-to-component interface) is formed on the outer surface 9 ofthe pad 3. The pad 3 is welded to the rod portion 2 at the joint 10 byelectron beam welding to produce a connecting rod 11 of a radial pistonmotor. 12 is a continuous weld bead formed by electron beam welding. Thepad 3 has a thickness T and an inner diameter D. The ratio T/D ispreferably 0.07 in the minimum. If the ratio were below 0.07,deformation of the pad 3 after welding wound be great. Thus by settingthe ratio T/D at a value over 0.07, it is possible to eliminate the riskthat the pad 3 would be deformed after welding.

The provision of the recess 6 in the rod portion 2 and the projection 7in the pad 3 for connecting them in interfitting relation offers theadvantage that the rod portion 2 and the pad 3 can be readily positionedrelative to each other with high dimensional accuracy. This facilitateswelding to join the rod portion 2 to the pad 3 at the joint 10 formed onthe outer surface 9 of the pad 3, with a result that the connecting rodcan be produced with good dimensional stability.

In the connecting rod according to the present invention, the sphericalportion 1, rod portion 2 and pad 3 are not formed integrally but formedseparately with one another, or at least the pad 3 is formed separatelyfrom the other parts. This offers the advantage that any suitablebearing alloy (bearing material) as desired may be selected for thebearing alloy layer or overlay 5 depending on the use to which theconnecting rod is put. That is, a bearing alloy of optimum qualitysuitable for the service can be selected as desired.

FIGS. 4-6 show a second embodiment of the invention, FIG. 4 is avertical sectional view of the connecting rod before assembly, FIG. 5 isa front view of the connecting rod after having been assembled and FIG.6 is a perspective view of the connecting rod portion joined to the padby welding.

In the first embodiment shown in FIGS. 1-3, the joint 10 is formed to beflush with the planar or flat portion 8 surrounding the projection 7 onthe outer surface 9 of the pad 3. This might degrade the quality of theweld formed at the joint 10 because a part of the energy of weldingwould be absorbed by the flat portion 8 due to impinging thereon whichis not in engagement with the rod portion 2 when the joint 10 is welded.

To eliminate this risk, in the second embodiment, an elevated portion 13of substantially the same diameter as the rod portion 2 having its topsurface spaced apart from the outer surface 9 of the pad 3 by a distanceW (preferably over 1 mm) on the pad 3, and a smaller projection 14 forconstituting a male-female engagement with the recess 6 of the rodportion 2 is formed on the surface of the elevated portion 13.

By the arrangement described hereinabove, the projection 14 of the padis inserted in the recess 6 of the rod portion 3 in interfittingrelation to form a joint 15 as shown in FIG. 5. Since the joint 15 isnot flush with the planar portion 8, there is no risk of the weld beingdegraded due to the energy of welding being absorbed partly by theplanar portion 8 which is not in contact with the rod portion 2, as inthe first embodiment. Thus it is possible to obtain a connecting rod ofa radial piston motor including a second weld. 17 is a weld produced byelectron beam welding.

The ratio of the thickness T of the pad 3 to the inner diameter Dthereof, namely, T/D is preferably over 0.07 as is the case with thefirst embodiment. The second embodiment can achieve the same results asthe first embodiment does in facilitating welding and enabling theconnecting rod to have dimensional stability because of the feature thatthe rod portion 2 is connected to the pad 3 by fitting the projection inthe recess to facilitate positioning of the rod portion and the padrelative to each other.

In the first and second embodiments shown and described hereinabove, theinterfitting portions consist of a projection formed in the rod portionand a recess formed in the pad. However, the invention is not limited tothis specific form of interfitting portions, and the rod portion may beformed with a recess and the pad may be formed with a projection withoutdeparting from the scope of the invention. Also, the rod portion and thepad may be each formed with not only one interfitting portion but also aplurality of interfitting portions, or the rod portion and the pad maybe each formed with one or a plurality of recesses so that they may beinterconnected by pins.

The invention is not limited to electron beam welding for joining therod portion to the pad. Depending on the service to which the connectingrod is subjected, brazing or friction welding may be utilized. The weldformed in the joint may not be continuous but formed in part of thejoint.

In both the first and second embodiments, the spherical portion and therod portion are described as being formed integrally with each other.The invention is not limited to these embodiments and the sphericalportion may be formed separately from the rod portion. In this case, therod portion may be joined directly to the spherical portion by weldingor welding may be effected after the two portions are connected togetherby interfitting.

What is claimed is:
 1. In a connecting rod of a radial piston motorhaving a spherical portion, a rod portion and a curved pad having athickness T and an internal diameter D,the improvement wherein said rodportion (2) is solid and provided at its one end with a recess (6), saidpad (3) being a composite bearing constituted by a metallic backinglayer and a bearing alloy layer on said backing layer, said backinglayer being provided on its surface adjacent to said rod portion with aprojection (7,14), said rod portion and said backing layer being joinedto each other by electron beam welding at the joint therebetween withsaid projection fitting in said recess formed in said rod portion;wherein said projection (14) extends from a large projection (13) ofdiameter substantially equal to the diameter of said rod portion, saidelectron beam welding at the joint being between said large projectionand said rod portion.
 2. A connecting rod of a radial piston motor asclaimed in Claim 1, wherein the ratio T/D of the thickness T of thecomposite bearing of said pad portion to the inside diameter D of saidbearing alloy layer is 0.07 or greater.